[nojwe]

My chain is laptop->USB->Schiit Modi Multibit->Woo Wa7 TP->HD800.

When my amp is off I get a low hum/static sound through my headphones, which I didn't think was possible. I imagine that means there is some interference/ground loop or something somewhere, but how do I got about diagnosing and fixing it?

Is it possible that this could cause damage to anything in the chain?

 

[Poganin]

Possibly a ground loop. Is your Schiit connected to the same power strip as the WA7? If not, connect them to the same power strip and check then.
Same thing happened to me between my Aune S6 and Feliks Audio Echo, but the noise was introduced over the USB cable. Disconnecting it from the S6 stopped the noise, but that obviously made the setup useless. However, plugging the S6 into the same power strip as the Echo stopped the noise, too.

 

[nojwe]

Interesting. They are both plugged into the same power strip. I'll try playing around with the plug setup to see if something is getting introduced there.

 

[buke9]

Interesting. They are both plugged into the same power strip. I'll try playing around with the plug setup to see if something is getting introduced there.

Did you turn the Modi off also? On my Yggdrasil if my Cavalli Liquid Carbon is fed by the Yggy via balanced and is not turned on my other amp a tube amp also connected to the Yggy is distorted turn it on and everything is fine again I know not the same thing but all things in the chain matters. I would also unplug the inputs to the amp from the modi as well to see if it is coming in that way.